The US intelligence community said the Iraq conflict was in many key ways a "civil war," a long-awaited finding immediately disputed by President George W. Bush's administration.
The conclusions contained in a National Intelligence Estimated cleared by 16 US spy agencies added new fuel to the debate over the US role in Iraq, plagued by escalating fighting between majority Shiite Muslims and minority Sunnis.
"The Intelligence Community judges that the term 'civil war' does not adequately capture the complexity of the conflict in Iraq," read the intelligence estimate presented to Bush.
"Nonetheless, the term 'civil war' accurately describes key elements of the Iraqi conflict, including the hardening of ethno-sectarian identities, a sea change in the character of the violence, ethno-sectarian mobilization, and population displacements."
The document also painted a bleak picture of the fighting in Iraq that has cost the lives of more than 3,000 US troops and tens of thousands of Iraqis since the 2003 invasion to oust dictator Saddam Hussein.
It warned that without quick action "the overall security situation will continue to deteriorate at rates comparable to the latter part of 2006" over the next 12 to 18 months.
The White House, under fire for its Iraq policy and plans to add 21,500 more US troops to the 132,000 already on the ground, has refused to brand the conflict a civil war with Americans in the crossfire.
Just before the intelligence estimate was issued by the National Director of Intelligence, US Defense Secretary Robert Gates again rebuffed the idea of a civil war.
"I think that the words 'civil war' oversimplify a very complex situation in Iraq," he told reporters at the Pentagon.
"I believe that there are essentially four wars going on in Iraq. One is Shia (Shiite) on Shia, principally in the south. The second is sectarian conflict, principally in Baghdad but not solely. Third is the insurgency, and fourth is Al-Qaeda," said Gates.
"It's not, I think, just a matter of politics or semantics. I think it oversimplifies. I think it's a bumper-sticker answer to what's going on in Iraq," he said.